Potency is an interesting subject because in theory one should have consume less amounts over the same time period for the same effect. In other words, smoking one potent joint, while carrying its own risks, is probably healthier than smoking n > 1 joints to get a similar effect.

Cannabis, the literal plant, is strong than the 70s, but it's not like humans haven't been making concentrates (hash, resins, etc.) for 1000s of years.